1. Field of the Invention
The present invention relates to a method for peeling a circuit or a semiconductor device that is composed of thin film transistors (hereinafter, TFTs), and a semiconductor device that is obtained by the method.
As used herein, the term “semiconductor device” refers to devices in general that operates by utilizing semiconductor characteristics. Each of an electro-optical device, a semiconductor circuit, and an electronic appliance is a semiconductor device.
2. Related Art
Technique for forming a TFT by using a semiconductor thin film (with a thickness of approximately from several to several hundreds nm) formed over a substrate having an insulating surface has attracted attention recently. The TFT has been widely applied to electronic devices such as an IC or an electro-optical device, and has been accelerated to be developed as a switching element of an image display device.
Various applications of an image display device have been expected. Especially, the image display device application for a cellular phone has attracted attention. Currently, a glass substrate or a quartz substrate are widely used, however, they have defects of being fragile and heavy. Hence, it has been tested that a TFT element is formed over a substrate having flexibility, typically, a flexible plastic film.
However, maximum process temperature should be lowered since the heat resistance of the plastic film is poor. As a result, the TFT formed over the plastic film cannot have so much excellent electric characteristics as that of a TFT formed over a glass substrate in the present situation. Therefore, a high-performance semiconductor element using a plastic film has not been realized.
Consequently, a technique of peeling an clement formed over a glass substrate from a substrate and transferring the element to another backing such as a plastic film is proposed.
The applicants propose peeling or transferring technique as disclosed in the following patent documents 1 or 2.
In the case of a very small device such as an IC, a semiconductor wafer is pasted onto an adhesive sheet to be divided as a chip unit, and the divided semiconductor clement is picked up from the adhesive sheet, then, the picked up semiconductor element is mounted in a circuit substrate constituting an IC card or the like. Since the semiconductor wafer is used, the IC had defects of being subjected to be injured or broken when being picked up.
Patent document 1: Unexamined patent publication No. Hei 8-288522
Patent document 2: Unexamined patent publication No. Hei 8-250745
It has been recently considered the possibility of utilizing “noncontact IC tag” (generally, referred to as noncontact data carrier) that can record and read out information out of touch for information management of goods or products, physical distribution management, and the like.
A semiconductor wafer that serves as a mother body for a semiconductor chip used for an IC card or a noncontact IC tag is expensive and unfit for mass-production.
A method for manufacturing the matrix type (multiple patterned type) that is mounted with multiple electronic component elements over a glass substrate and divided into individual pieces as a product has been distributed. A small device is preferably manufactured over a large substrate in consideration for mass-production.